Collective fluorescence and decoherence of a few nearly identical quantum dots

We study the collective interaction of excitons in closely spaced artificial molecules and arrays of nearly identical quantum dots with the electromagnetic modes. We discuss how collective fluorescence builds up in the presence of a small mismatch of the transition energy. We show that a superradiant state of a single exciton in a molecule of two dots with realistic energy mismatch undergoes a two-rate decay. We also analyze the stability of subdecoherent states for nonidentical systems.

Figure 1

(a) The fidelity for a subradiant state for $V=0$ and $\Delta =0.8\mu \mathrm{eV}$ (solid), $2\mu \mathrm{eV}$ (dashed), and $20\mu \mathrm{eV}$ (dotted). (b) The fidelity for $V\ne 0$, $\Delta =2\mu \mathrm{eV}$. Inset in (a) shows the fidelity of a superradiant state for different dots without interaction ($\Delta =4\mu \mathrm{eV}$, solid) and for interacting dots ($\Delta =2.68\mu \mathrm{eV}$, $V=2.97\mu \mathrm{eV}$, dashed), compared to an exponential decay with the rates $\Gamma$ and $2\Gamma$ (dotted and dash-dotted lines, respectively).

Figure 2

The exciton occupation for sub-(a) and superradiant (b) states for $\Delta =1\mathrm{meV}$. The inset in (b) shows the values of the occupation decay rates.

Figure 3

(a) Photon emission rate for a superradiant state for $V=0$ and (b) for $V\ne 0$, $\Delta =2\mu \mathrm{eV}$.

Figure 4

The fidelity for two subradiant states $\mid {\psi }_{\mathrm{a}}⟩$ (a) and $\mid {\psi }_{\mathrm{b}}⟩$ (b) of 4 QDs for various combinations of parameters. The parameter values given in (b) are valid for both figures.

Figure 5

Photon emission rate for a superradiant state of 4 QDs for $V=0$ (a) and for $V\ne 0$ (b).